The invention relates to an in-line vacuum coating system having a vacuum chamber, at least one coating unit and a carrier, that can be moved through the vacuum chamber, for holding tubular substrates.
When a carrier is used in in-line continuous systems, the substrates are usually statically fixed in order then to be coated as they pass a coating source. A carrier should be understood in the following to mean a substrate support in which the tubular substrates can be positioned in a spaced-apart manner one above another and can be rotated about their longitudinal axes.
In the case of two-dimensional substrates this is readily possible, whereas in the case of rotationally symmetrical substrates, such as pipes, which are also much longer than customary coating sources, the substrate axes are rotated in the horizontal plane through 90° with respect to the coating source.
In order also in this case to ensure uniform coating while passing a coating source, such substrates are arranged on a carrier. As a rule, a plurality of substrates are arranged at the same time on a carrier.
In order to obtain high coating homogeneity on the lateral surface of the substrate, the substrates not only to have be moved in the direction of the longitudinal axis relative to the source, but also have to be rotated about their longitudinal axis. For this purpose, it is necessary to have two drives, which have to be adjustable independently of one another in order that the feed rate of the carrier and the rotational speed of the substrates can be set appropriately. In this way, the necessary coating homogeneity of the helically applied coating can be achieved, wherein the coating should extend without interruption over the entire surface of the substrates.